Process of inhibiting corrosion



nited St Patent mm P a'tented July 19, 1960 PROCESS OF INHIBITING CORROSION Aaron Sterlin, Chicago, 111., assignor to Nalco Chemical Company, a corporation of Delaware No Drawing. Filed Oct. 24, 1956, Ser. No. 617,933

7 Claims. (Cl. 252-392) This invention relates to a process of inhibiting corrosion of metals caused by the presence of waterin' aqueous and non-aqueous liquids.

The present application is directed toward subject matter which was required to be divided from my copending application Serial No. 280,197, filed Apr. 2,. 1952,

and is a continuation-impart ofsaid copending application which has now matured into US. Patent 2,773,879. One of the Objects of theinvention is to 'providea new and improved method of treating metals to prevent corrosion caused by water in aqueous liquids or in liquids which are predominantly non-aqueous butcontain minor amounts of water.

A further object of the invention is to provide-a method of inhibiting corrosion of ferrous metals. Other Objects will appear hereinafter.

In accomplishing these objects in accordance with the invention it has been found that new and improved re idine wherein the'carbon atom in the 2-position is linked to a higher aliphatic hydrocarbon group containing at least 8 carbon atoms, the carbon atomin the 4- position is linked to a member from the group consisting of hydrogen and lower aliphatic hydrocarbon groups containing not more than 6 carbon atoms, the carbon atom in the 5-position is linked to a member from the group consisting of hydrogen and lower aliphatic hydrocarbon groups containing not more than 6 carbon atoms, there being at least one hydrogen atom on each of the carbon atoms in the 4- and 5-positions, and the nitrogen atom in the 1-position is linked to a member from "the group consisting of hydrogen and lower aliphatic groups containing not more than 6 carbon atoms, said 'carboxyl groups. The invention also contemplates the use of mixtures of such salts.

The inhibiting compounds can also be characterized as monoglyoxalidine salts of said organic aliphatic di carboxylic acids or digl-yoxalidine salts of such acids, de-

pending upon whether one or two mols of the glyoxalidine is reacted with the organic aliphatic dicarboxylic acid.

If only one mol of the glyoxalidine is reacted thc resultant compoundis amonoamine salt containing portion. of, the molecule is derived by reacting together a free carboxylic acid group- If two mols of the glyoxalid'ine are reacted the resultant compound is a di amine salt. The glyoxalidines employed as starting materials are made by well known procedures by reacting a fatty acid with an aliphatic polyamine with the elimination of water as described, for example, in Wilson, US.

Patent 2,267,965 and Wilkes et al., US. Patent 2,268,273.

l The glyoxalidines with which the present invention is partic'tllarl'y concerned are those in which the glyoxalidine one of the acids from the group consisting of lauric acid, myristic acid, palmitic acid, oleic acid and stearic acid, with an aliphatic polyamine from the group consisting of aminoethylethanolamine, diethylenetriamine and triethylenetetramine'. When the glyoxalidine' is derived from aminoethylethanolamine the resultant product contains a hydroxyethyl group in the 1-position. When the glyoztalidine is derived from diethylenetriamine the resultant product contains an aminoethyl group in the 1- position, and when the glyox'alidine is derived from triethylenetetramine the resultant product contains a (2- aminoethyD-aminoethyl group in the 1- position.

The number of carbon atoms in the aliphatic hydrocarbon group in the 2-position is always one less than that in the aliphatic carboxylic acid from which the glyoxalidine is derived. Thus, if the glyoxalidine is made from lauric acid the hydrocarbon group in the 2- position will contain 11 carbon atoms. If the glyoxal- Qidine is made from oleic acid the hydrocarbon group in the 2- position will be a heptadecenyl group containing 17 carbon atoms. The hydrocarbon group in the 2-position preferably contains 13 to 17 carbon atoms for the purpose of the present invention.

Specific examples of glyoxalidines that can be reacted with sebacic acid, 'dilinoleic acid andother long chain organic aliphatic dicarboxylic acids in preparing salts suitable for the purpose of the invention are:

.4-methyl-2-tridecyl glyoxalidine, '4-methyl-2-pentadecyl glyoxalidine,

4-methyl-2-heptadecyl glyoxalidine, 4-methyl-2-heptadecenyl glyoxalidine.

The organic aliphatic dicarboxylic acid salts are pre pared by mixing a glyoxalidine of the type described and an organic aliphatic dicarboxylic acid of the type described in mol ratios of 1:1 in case it is desired to prepare the monoamine salt, or 2:1 in case it is desired to prepare the diamine salt, and warming the reaction mixture at temperatures sufficient to melt the dicarboxylic acid if it is a solid for 5 to 15 minutes with or without a catalyst until homogeneous materials are obtained.

In the practice of the invention it has been found that especially goodresults in inhibiting corrosion in gasoline containing water have been obtained by employing as the corrosion inhibiting agent the reaction products of sebacic acid and 1-(2-hydroxyethyl)-2-heptadecenyl glyoxalidine. Especially good results have been obtained with the reaction product derived by reacting two mols of said glyoxalidine with one mol of sebacie acid. Excellent results have also been obtained by employing as the gasoline additive the product obtained by bringing together a polymer acid containing approximately two carboxy groups and 34 to 36 carbon atoms and 1-(2- hydroxyethyl)-2-heptadecenyl glyoxalidine in approximately equal weight proportions.-

In order to evaluate the invention tests were made in hydrocarbon fuels to which water had been added.

The organic aliphatic dicarboxylic acid salt of the glyoxalidine of the type previously described was prepared for use as a 10% by weight concentrate in a suitable solvent.

The test specimens were hot rolled mild steel rods A1. x 2%" of which a 2%" length was polished with No. 3/0 emery cloth.

The test medium, for example, gasoline, was placed in a 25 x 150 mm. screw cap tube. To 40 ml. of the test medium were added first the inhibitor solution previous- 1y described and after mild agitation 10% by volume of distilled water which had been equilibrated with air. The capped tube was then mechanically agitated at room temperature (75 F.) for six hours by end over end tumbling.

The test solution was then transferred to a numbered 25 x 150 mm. test tube and the water and hydrocarbon phases were permitted to separate. The test specimen was inserted in the tube so that a part was exposed to the lower phase (water) without contacting any part of the container. The tube was not disturbed for the 72- hour test duration.

Other tests were set up as described above with selected materials in which 1% water instead of 10% was used.

After completion of the test the specimen was removed, rinsed with acetone and air dried. It was then evaluated on the extent of visible corrosion. Each test was made in duplicate. If both specimens were not visibly corroded the material was classed as eifective and if both appeared to be corroded the material was called ineffective. Wherever one of the pairs was uncorroded and the other corroded the test was repeated. If, after re testing, either specimen was corroded the material was judged to be ineifective at the tested concentration. This criterion is identical with that used in ASTM D-665-49T.

The following examples illustrate some of the results obtained when compositions falling within the scope of the invention were evaluated in the manner just described.

Example I The sebacic acid salt derived by reacting two mols of l-(Z-hydroxyethyl)-2-heptadecenyl glyoxalidine with one mol of sebacic acid at a temperature of about 133 C.

for about 5 to 15 minutes when tested under the foregoing conditions in Standard Red Crown gasoline to which distilled water had been added was effective in inhibiting corrosion of the test specimens at concentrations of 10 parts of said amine salt per million parts of gasoline in a series of six tests.

In a series of three tests at a concentration of 25 parts per million the said glyoxalidine sebacic acid salt completely inhibited corrosion under the test conditions described. I

In a series of six tests at a concentration of 5 parts per million in said gasoline under the same test conditions there was slight to moderate corrosion of the test specimens.

Example II When the same corrosion inhibiting composition was 4 tested under agitated conditions according to ASTM method D-665-49T using room temperature instead of 140 F. and strips of SAE1018 steel instead of SAE- 1020 or SAE-1025 steel the aforesaid diglyoxalidine sebacic acid salt was effective in preventing corrosion at a concentration of 0.31 part per million in the gasoline.

Example HI Under the same test conditions as in Example II at a concentration of 0.16 part per million in the gasoline slight corrosion of the test specimens was obtained. At a concentration of 0.08 part per million heavy corrosion was obtained. Thus, the effective minimum amount in inhibiting corrosion in gasoline with said composition under agitated conditions is around 0.3 part per million and under static conditions around 5 to 10 parts per million.

Example IV Results similar to those in Example I were obtained with the reaction product derived by reacting one mol of 1-(2-hydroxy ethyl) -2-heptadecenyl glyoxalidine with one mol of sebacic acid at a temperature of about 133 C. for about 5 to 15 minutes.

Example V The monoamine salt of a dimer acid was prepared by heating together at a temperature up to 100 equimolecular proportions of 1-(2-hydroxyethyl)-2-heptadecenyl glyoxalidine and a dimer acid containing about by weight of dilinoleic acid. This product was eifective in inhibiting corrosion in a gasoline-water system under the test conditions previously described at a concentration of 25 parts per million.

Example VI The reaction product was prepared by reacting together two mols of 1-(2-hydroxyethyl)2-heptadecenyl glyoxalidine and one mol of a dimer acid containing about 85 by weight dilinoleic acid. This product was eflective in inhibiting corrosion in a gasoline-water system when tested accordng to the static corrosion test previously described at a concentration of 25 parts per million.

The solvent which is used to dissolve the active effective ingredient is subject to some variation depending upon the solubility characteristics of the particular compound employed. In some cases, even though the corrosion inhibiting compound is insoluble in a particular solvent it will dissolve in a combination of solvents. For instance, the compound tested in Example I is soluble in denatured ethyl alcohol, soluble in Indocene 90 (a petroleum fraction high in aromatic compounds and naphthenes) soluble in 99% isopropanol, insoluble in virgin gas oil and soluble in xylene. This product dissolves satisfactorily in a mixture of xylene and naphtha. As an illustration, where the corrosion inhibiting ingredient is to be added to gasoline a suitable concentrate has the following composition:

Ingredients: Weight percent Sebacic acid salt of Example I 12 Xylene 35 'Naphtha (flash point 80 to F.) 53

Similarly other compositions can be prepared using suitable solvents.

It will be understood that the effective corrosion inhibiting ingredient can be added directly to the hydrocarbon liquid provided it is soluble therein. However, the amounts required are so small that it is preferable to prepare a solution of the active ingredient containing about 5 to about 15% thereof, the remainder being a suitable solvent which dissolves the corrosion inhibiting ingredient and is miscible with the medium to which the solution is to be added.

It will be understood that some variations can be made 'Iddil'l value ranger in the preparation of the corrosion inhibiting chemicals and in the procedures employed in using such chemicals. As examples of other magemm aliphatic dicarbojtylic acids which can be reacted with any of the glyoxalidines previously described there may be mentioned the acids known in the trade as VR fatty acid and VR-l acid.

' VR fatty acid is an organic carboxy acid material which is a vegetable residue resulting from the distillation of soap stock. This material contains ester bodies sad has the following characteristics:

Acidvalue 45 Saponification value .i... 150

Color (Bartlett) Viscosity (Zahn G at 75 C.') ..sec

VR-1 acid is a mixture of polybasic acids with an average molecular weight of about 1000. It has an average of slightly less than two carboxylic acid groups per molecule. It is a by-product from the production of 'sebacic acid by the caustic fusion of castor oil, consists principally of polymerized linoleic acid, contains dimerized, trimen'zed and higher polymerized linoleic acid, and is a dark amber, rather viscous liquid. A typical sample of VR-l acid has the following analysis:

Acid number 150 Iodine number 36 Saponification number 172 Unsaponifiable matter percent 3.7, 3.5 Moisture content percent 0.86

One of the important advantages of the present invention is that the addition of the compositions herein described to gasoline in the quantities which are effective in inhibiting corrosion has no adverse etfects such as gum formation. In actual tests using a corrosion inhibiting composition consisting of 12% by weight of the product obtained by reacting two mols of 1-(2-hydroxyethyl)-2-heptadecenyl glyoxalidine with one mol of sebacic acid, 35% by weight Xylene and 53% my weight of naphtha, there was a decrease in gum formation in the gasoline from 2.8 mg. per 100 ml. to 1.0 mg. per 100 ml. at a concentration of parts of the corrosion inhibiting chemical (84 parts of the solvent solution of said chemical) per million parts by weight of gasoline.

The invention is further illustrated by the following example:

Example VII A composition was prepared having the following formula:

Percent by weight Ingredients Century D-75 acids 1 25 1-(2-hydroxyethyl)-2-heptadecenyl glyoxalidine 25 Bronoco Hi-Sol 50 This mixture of polymer acids containing approximately two carboxylic acid groups per molecule and having properties generally similar to VR-l acid previously described.

ASTM test D-66552T known as the turbine oil rusting test at 75 F., a concentration of 25 parts per million of the corrosion inhibiting composition was elfective in preventing corrosion in gasoline, 115-145 octane aviation gasoline, 100130 octane aviation gasoline, 100-130 octane aviation gasoline and No. 2 high speed diesel fuel oil. Since this test involves the use of synthetic sea water the results indicate particularly the value of S the invention in ocean going tanke'i's where rust-ing due to the presence of sea water is a problem.

In static tests carried out in the manner previously describedherein in the presence of deionized water 25 parts per million of this corrosion inhibiting composition were also effective in inhibiting corrosion in Standard Red Crown gasoline and the three types of aviation gasoline described above. Y In general, depending upon the particular hydrocarbon liquid, the quantity of the active salt of the organic aliphatic dicarboxylic acid employed tot-"the purpose of the invention may vary from a fraction of a part permillion as shown by Examples II and III to 1000 parts per million. However, it will be recogniied that it is desirable to use as small a quantity of the corrosion inhibiting composition as will be effective to accomplish the purpose and in most instances good results are obtained with proportions within the range of /2 to 25 parts of the glyoxalidine salt per million parts of hydrocarbon liquid. The inhibiting compounds employed for the purpose of the invention can also be employed in similar dosages to retard or inhibit corrosion of 'metal equipment which comes in contact with mine waters, such as uranium ore processing Waters, phosphate ore processing waters, taconite and other iron ore processing waters, coal mine waters, and the like. Additionally, the inhibiting compounds herein described can be employed for the downhole treatment of oil and gas wells to minimize corrosion to the equipment normally caused by mixtures of hydrocarbons and water present in such Wells.

The term glyoxalidine refers to a compound having the following structural formula wherein R is an aliphatic hydrocarbon radical; R, Y and Z are either hydrogen or an aliphatic group, it being understood that for the purpose of the present invention R, R, Y and Z are further restricted in the manner previously described. It should also be noted that in the preferred compounds of the present invention R is composed of carbon and hydrogen atoms, Y and Z are either hydro gen or groups consisting of carbon and hydrogen, and R is either hydrogen, a group consisting of carbon and hydrogen, a group consisting of carbon, hydrogen and nitrogen, or a group consisting'of carbon, hydrogen and oxygen. In other words, in the preferred compounds with respect to R the atoms in the group are selected from the group consisting of hydrogen, carbon, nitrogen and oxygen.

The invention is hereby claimed as follows:

1. A method of inhibiting corrosion of metals caused by the presence of Water in aqueous and non-aqueous liquids which comprises applying to said metals a salt of an organic aliphatic dicarboxylic acid containing at least 10 carbon atoms in a hydrocarbon structure and a glyoxalidine wherein the carbon atom in the 2-position is linked to a higher aliphatic hydrocarbon group containing at least 8 carbon atoms, the carbon atom in the. 4-position is linked to a member from the group consisting of hydrogen and lower aliphatic hydrocarbon groups containing not more than 6 carbon atoms, the carbon atom in the 5-position is linked to a member from the group consisting of hydrogen and lower aliphatic hydrocarbon groups containing not more than 6 carbon atoms, there being at least one hydrogen atom on each of the carbon atoms in the 4- 'and 5-positio-ns, and the nitrogen atom in the 1- position is linked to a member from the group consisting of hydrogen and lower aliphatic groups containing not more than 6 carbon atoms, said last named lower aliphatic groups being composed of atoms from the group consist ing of hydrogen, carbon, nitrogen and oxygen.

a salt of sebacic acid.

3; A process as claimed in claim 1 in which said salt is a salt of a polymerized fatty acid containing 34 to 36 carbon atoms and approximately two carboxylic acid groups.

4. A process as claimed in claim 1 in which said glyoxalidine contains a higher aliphatic hydrocarbon group having 13 to 17 carbon atoms, inclusive, in an acyclic chain in the 2-position.

5 A process as claimed in claim 1 in which said member linked to the nitrogen atom in the 1-position is a 2-hydroxyethyl group.

6. A method of inhibiting corrosion of ferrous metals caused by the presence of water in aqueous and nonaqueous liquids which comprises applying to such metals '8 a sebacic acid salt of l-(Z-hydroxyethyl)-2-heptadecenyl glyoxalidine.

7. A method of inhibiting corrosion of ferrous metals caused by the presence of Water in aqueous and nonaqueous liquids which comprises applying to such metals a polymerized fatty acid salt of l-(2-hydroxyethyl)-2-l1eptadecenyl glyoxalidine in which the polymerized fatty acid contains 34 to 36 carbon atoms and approximately two carboxylic acid groups.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,227 Blair et al. May 9, 1950 2,632,695 Landis et al Mar. 24, 1953 2,668,100 Luvisi Feb. 2, 1954 2,819,284 KWan-Ting Shen Jan. 7, 1958 

1. A METHOD OF INHIBITING CORROSION OF METALS CAUSED BY THE PRESENCE OF WATER IN AQUEOUS AND NON-AQUEOUS LIQUIDS WHICH COMPRISES APPLYING TO SAID METALS A SALT OF AN ORGANIC ALIPHATIC DICARBOXYLIC ACID CONTAINING AT LEAST 10 CARBON ATOMS IN A HYDROCARBON STRUCTURE AND A GLYOXALIDINE WHEREIN THE CARBON ATOM IN THE 2-POSITION IS LINKED TO A HIGHER ALIPHATIC HYDROCARBON GROUP CONTAINING AT LEAST 8 CARBON ATOMS, THE CARBON ATOM IN THE 4-POSITION IS LINKED TO A MEMBER FROM THE GROUP CONSISTING OF HYDROGEN AND LOWER ALIPHATIC HYDROCARBON GROUPS CONTAINING NOT MORE THA 6 CARBON ATOMS, THE CARBON ATOM IN THE 5-POSITION IS LINKED TO A MEMBER FROM THE GROUP CONSISTING OF HYDROGEN AND LOWER ALIPHATIC HYDROCARBON GROUPS CONTAINING NOT MORE THAN 6 CARBON ATOMS, THERE BEING AT LEAST ONE HYDROGEN ATOM ON EACH OF THE CARBON ATOMS IN THE 4- AND 5-POSITIONS, AND THE NITROGEN ATOM IN THE 1POSITION IS LINKED TO A MEMBER FROM THE GROUP CONSISTING OF HYDROGEN AND LOWER ALIPHATIC GROUPS CONTAINING NOT MORE THAN 6 CARBON ATOMS, SAID LAST NAMED LOWER ALIPHATIC GROUPS BEING COMPOSED OF ATOMS FROM THE GROUP CONSISTING OF HYDROGEN, CARBON, NITROGEN AND OXYGEN. 